Skin conductance responses (SCR, "sympatho-galvanic reflex") were measured before and during spinal analgesia in 17 patients scheduled for transurethral surgery. Responses were provoked by standardized electrical stimulation over the clavicle opposite to the recording side; alternatively, a short deep breath, pinching, verbal stimuli or sharp sounds were used. Measuring sites (two electrodes 6 cm apart) were the hand, levels T5, T9, T12-L1 and the foot. Spinal analgesia reached a median cephalad level of T4 (mean T4, range +/- 3 segments) 20-25 min after injection. SCR was markedly depressed in the foot in 15 of 17 patients, at T12-L1 in 12 of 17, at T9 in 10 of 17, at T5 in 9 of 16 and in the hand in 6 of 17. Total abolition of the SCR in the foot was accomplished in only seven cases and sympathetic activity reappeared long before regression of analgesia or motor blockade was observed. In four cases of five with an analgesic level T1-T2, the SCR was preserved in the hand. No consistent correlation between blood pressure change and SCR-change was seen. The conclusion from this study is that preganglionic sympathetic B-fibres are more difficult to block than A-fibres during spinal analgesia. The duration of sympathetic blockade was far shorter than analgesia and motor blockade. Thus, sympathetic blockade during spinal analgesia seems to be far less extensive than that described in the literature.

Spinal analgesia using 22.5 mg glucose-free bupivacaine, given either as 3.0 ml of 0.75% solution or 4.5 ml of 0.5% solution was studied in a double-blind fashion in 40 patients scheduled for transurethral surgery. No differences in onset, duration and regression of analgesia or motor blockade were noticed, indicating that dosage (in mg) is more important than either volume or concentration when glucose-free bupivacaine solutions are used for spinal analgesia. The cardiovascular effects were small and no side-effects attributable to the spinal anaesthetic were seen.

At present there is a lack of information concerning haemodynamic changes related to the degree of sympathetic blockade during spinal analgesia. In this investigation, involving 36 patients, changes in haemodynamic parameters were studied in 30 patients receiving spinal analgesia and in six patients having "sham spinal" analgesia. Three local anaesthetic solutions were used: bupivacaine without and with glucose and tetracaine with glucose. Skin conductance responses were used to evaluate changes in provoked sympathetic activity. It was found, as in previous studies, that a complete block of sympathetic activity in the foot was seen in only 60% of patients with an average analgesic level of T4. A partial sympathetic blockade was registered up to and above the level of analgesia. In 25/30 cases only minor alterations in cardiac output, heart rate, stroke volume, mean arterial pressure and systemic vascular resistance were seen in spinal analgesia whose level reached on average T4-5. In five cases in whom analgesia reached T4-3, mean arterial pressure fell greater than or equal to 30% with a well-preserved cardiac output, but with complete sympathetic blockade up to T5 and in two cases also in the hand. Only minor differences were observed between the different anaesthetic solutions.

Non blanchable erythema, i.e. stage I pressure ulcer, is common in patients in acute and geriatric care and in nursing homes. Research has shown that this type of lesions is prone to develop into more severe pressure ulcers. The peripheral skin blood perfusion is of major importance for the development of pressure ulcers. The aim of this study was to explore the peripheral skin blood perfusion over time, in areas with non blanchable erythema and in corresponding undamaged areas on the opposite side of the body. A total of 19 measurements were performed, over time, using a laser Doppler perfusion imager. The blood flow distribution profiles over areas with non blanchable erythema and undamaged skin were found to be different. As the area of the non blanchable erythema decreased, the blood perfusion distribution profiles gradually became more heterogeneous; an area of high blood perfusion in the centre of the lesions was seen and the perfusion successively decreased closer to the edge. These results indicate that there are differences in blood perfusion between skin areas of non blanchable erythema and undamaged skin. The results also indicate that the visible redness in areas with non blanchable erythema is related to altered blood perfusion. The skin blood perfusion also seems to increase in relation to the size of the non blanchable erythema.